Furnace for heating slabs and the like and conveyor for use thereon



April 30, 1968 G. R. SOPCHACK FURNACE FOR HEATING SLABS AND THE LIKE AND CONVEYOR FOR USE THEREON 2 Sheets-Sheet 2 m T N E V m Filed Dec. 19, 1966 ATTORNEYS.

United States Patent 3,380,722 FURNACE FOR HEATING SLABS AND THE LIKE AND CONVEYOR FOR USE THEREON George R. Sopchaek, New Kensington, 1a., assignor to Titzel Engineering, Inc., Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 19, 1966, Ser. No. 692,710 7 Claims. (Cl. 263-6) In the rolling or forging of metal, preformed pieces of metal in the shape of slabs, billets, plates or the like must be heated to a temperature at which the metal may be worked, and this application is for a furnace for this purpose, and particularly to a conveyor for supporting the work pieces as they travel from the charging to the discharging end of the furnace.

In the following description, particular reference will be made to a slab heating furnace and slabs, but it will be understood that this is by way of illustration, and that the invention is applicable to the heating of work or work pieces of various kinds.

Slab heating furnaces are usually, but not necessarily, constructed in such manner that the slabs enter at one end, pass through a succession of zones, and emerge from the opposite end. It is usual for the slabs to move in succession so that a slab is pushed in at the charging end and another will be ejected from the discharge end. The slabs are generally supported on parallel metal skids which are water-cooled to protect them from the heat. Sometimes the skids are horizontal, and sometimes they are inclined downward toward the discharge end. As will hereinafter appear, the present invention is applicable to either horizontal or inclined slab supports.

The present invention provides in a furnace a support to replace the conventional skids, which support is herein termed a conveyor in which the slab or other work piece rests and moves along a water-cooled guide in which there is a continuous progression of high temperatureresistant balls that roll in the guides. These balls, upon reaching the end of the guide or guide section, enter a tube that is surrounded by cooling water or other cooling medium and return to the starting end of the guide.

Since the slabs make only point contact with the balls, being tangent thereto, the heat path from the slabs into the water-cooled trough through the balls is small at any time and these points of contact are continuously changing with the movement of the slabs, so that the heatconducting path is continuously changing.

Whereas the usual water-cooled skids necessarily result in cold spots in the work piece where the metal rests on water-cooled skids, which in turn requires overfiring or overheating the mass of the billet, the present invention will substantially reduce or eliminate such cold spots and avoid overfiring or overheating. Moreover, furnace gases will have more effective contact with the slabs on the under side of the conveyor. The furnace may thus operate more efficiently and the slab or other work piece benefit by more uniform heating and reduction of skid marks will result.

By reason of the effective water-cooling arrangement, the simplicity of its construction, maintenance problems are reduced with the resulting loss from down time caused by repairs. Resistance to the pushing of the billets through the furnace is reduced and if the conveyors are inclined, gravity will further reduce the power required for moving the work pieces.

The invention has for its objects therefore to provide a unique conveying support for use in work piece heating furnaces which will eliminate or reduce disadvantages present with skid heretofore used, and which is simple, rugged and efiicient.

3,33%,722 Patented Apr. 3%), 1968 A further object of the invention is to provide a work piece heating furnace having work-supporting conveyors therein which are capable of withstanding intense heat, and which will enable slabs or other objects to be more uniformly heated, and which, while being water-cooled, provide only a small and more or less constantly changing heat-conducting path from the slabs or other objects to the water-cooled supports.

These and other objects and advantages are secured by my invention as will be apparent to those skilled in the art from the following detailed description of a preferred embodiment of the invention in conjunction with the accompanying drawings. In the drawings:

FIG. 1 is a schematic view in longitudinal vertical section with areas thereof broken away of one form of slabheating furnace incorporating the invention;

FIG. 2 is a side elevation on a larger scale, partly in section, showing opposite end portions of one of the conveyors;

FIG. 3 is a transverse section in the plane of line 11-11 of FIG. 2, but showing two of the conveyors as they are positioned in spaced side-by-side relation in the furnace; and

FIG. 4 is a view similar to FIG. 2 showing intermediate sections of the conveyor where the conveyor is made up in modules or sections.

Referring to the drawings, wherein corresponding reference numerals designate corresponding parts throughout, 2 designates generally a known form of a slab-heating furnace, providing a combustion space, or one zone thereof if it is a multiple zone furnace. The charging end is designated 3, and 4 is the discharge end. There are two or more parallel conveyors 5 extending lengthwise of the furnace on which the slabs 6 indicated in broken lines, or other work pieces are supported, and along which they move lengthwise through the furnace.

At the receiving or charging end of the furnace these conveyors may extend outwardly beyond the end wall of the furnace to a pusher (not shown) by means of which the slabs are pushed onto the conveyor and through the furnace. The slabs or work pieces form a continuous procession, so that as one is pushed on the receiving end of the conveyor a heated slab, having traversed the length of the furnace, is pushed off the discharge end.

Each of the parallel conveyors 5 in the furnace comprises a hollow elongated metal section 7 that may be constructed as a continuous member, or which may be formed of individual lengths rigidly connected, as hereinafter more fully described. This hollow supporting member is here shown, and as best seen in FIG. 3, as thickwalled, large-diameter tube. It has a closure 8 at the entering end of the furnace and a closure 9 at the opposite end. There is a water inlet pipe ltl at the receiving end of the conveyor which is connected with a source of water supply (not shown) and there is a water outlet pipe 11 at the opposite end.

Carried on the top of hollow section 7 is a rail 12 having a groove 13 in the top thereof which is nearly halfcircular in section. There is a continuous series or progression of high temperature-resistant independent rolling elements preferably in the form of balls in the groove, each ball 14 contacting the adjacent ones.

At each end of the hollow section the rail terminates in a tubular guide designated 15 at one end and 16 at the other. These guides each curve downwardly from the rail through an arc of about The tubular curved guides are of a diameter to freely receive the balls 14, but keep them in line. There is a straight tubular guide 17 inside the hollow section 7 connecting the two guides 15 and 16 and forming therewith a continuous tubular guide terminating at opposite ends of the grooved rail 12. Where the curved guides pass from the exterior to the interior of the tubular supporting member, they are welded or otherwise sealed to prevent the escape of water from the interior of the tubular supporting member. The procession of balls 14 extends not only along the grooved top rail, but through the curved guides 15 and 16 and the connecting reach 17, forming a complete elongated loop of these balls.

When the balls are in the grooved tracks, their tops extend above the sides of the grooved track so that when the slabs or other generally fiat work pieces are placed on the conveyors, the under sides thereof are tangent to the balls 14 on which they rest, practically in point contact. For this reason the heat-conducting path from the work piece through the balls to the water-cooled rails 12 at each of the several points of support is small. The rail itself, being on the water-cooled tubular supporting member 7, is protected from excessive over-heating. As the work pieces move along on the balls, the balls themselves will roll along in the grooves. Since the curvature of the groove 13 conforms closely to the area of the balls, the balls having a radius only slightly less than the radius of the curve of the groove 13, they will dissipate much of their heat into the rails. As the balls move along the rails, all of the balls in the continuous loop will move. At the discharge end of the rail, the balls enter the tubular guide 16 and travel through the guide 17 which is surrounded by water, and eventually move up the return guide 15 to the grooved rail 12. In the groove 13 the individual balls are held in line by the groove and by the work pieces, and in the return reach, the tube turns 15 and 16 and the connecting reach 17, while being of such diameter that the balls are freely movable therethrough, nevertheless confining the balls to a single line of travel. Thus there is no need for individual cages or other confining means that would require lubrication or be destroyed by heat.

In order to keep the groove 13 clear of scale and dirt, the walls forming the groove 13 have downwardly-slanted openings 18 therethrough at frequent intervals so that the grooves will at all times be cleared of obstructions that might normally be expected to otherwise collect therein.

While the hollow supporting section 7 may be made in a single length, it may be desirable in most cases to construct the conveyor in modules or sections which may be joined together. In FIG. 4, such a modular construction is shown for sections between the two ends. In this construction, the tubular supporting section 7 is comprised of short lengths 7a. Confronting end plates 8a at each end of the section have an opening 81) therein which registers with a corresponding opening in an abutting similar section. These openings may be threaded to receive a connecting nipple and the sections may be welded, flangejointed, or otherwise joined to one another, thus forming a continuous water passage. In this case the terminal sections would be closed at one end as shown in FIG. 2 and have end plates similar to 8a of FIG. 4, thereby providing the water inlet and discharge sections at the end. All other parts of each section, such as the ball guides, balls, etc. are the same as above described in FIGS. 2 and 3.

This modular construction not only reduces manufacturing and shipping problems and standardizes design, but enables a section which becomes damaged in use to be replaced without complete replacement of the conveyor. In a zoned furnace the firing rate is higher at the charging end where the slabs are cold, but higher overall temperatures may exist in the discharge zone where differential temperature between the slabs and furnace gases is lower. It is therefore important to be able to replace sections of the conveyor rather than the complete conveyor, since wear and destructive influences will be diiferent along difierent zones of the furnace. Also, by having the conveyor in sections, the individual balls will be exposed for shorter periods of time. Also, with shorter sections, each individual ball will encounter less pressure from its 4 neighbors than where there are very long loops, so that the balls will move more freely with the slabs or other work pieces.

In some cases, small cylindrical rollers may be used in place of balls, particularly if they are of greater diameter at the center than at the ends, so that their surface is curved or semi-spherical so that they do not make line contact with the work and with each other. Generally spherical balls are more satisfactory.

While I have shown and described a particular furnace and preferred embodiment of my invention, various changes and modifications may be made therein within the contemplation of the appended claims.

I claim:

1. A conveyor for use in a furnace for heating slabs and the like comprising:

a hollow elongated supporting member,

means for circulating a cooling medium through the hollow supporting member,

a grooved track carried on the hollow supporting memher,

a curved tubular guide at each end of the track extending into the interior of the hollow supporting member and a tubular guide inside the hollow supporting member extending lengthwise of the supporting member and connecting the inner ends of the curved tubular guides to form with the track a continuous elongated loop around which rolling elements may travel, and

a continuous progression of separate rolling elements in abutting contact movable around said elongated loop with their peripheries of those elements which are in the track projecting above the track so that the work pieces may be supported thereon.

2. A conveyor as defined in claim 1 in which the rolling elements have specially curved work-contacting surfaces.

3. A conveyor as defined in claim 1 in which the rolling elements are balls.

4. A conveyor as defined in claim 1 in which the conveyor is parallel with another similar conveyor.

5. A conveyor as defined in claim 1 in which a plurality of said supporting members, each with its own track guides forming with the track an elongated loop and progression of separate rolling elements are rigidly connected in end-to-end relation.

6. In a furnace comprising a structure forming an elongated combustion chamber through the length of which objects to be heated are moved from a charging end to a discharge end on parallel work-supporting means, wherein each of the parallel supporting means comprises:

a track,

a hollow supporting structure on which the track is mounted,

means for effecting the circulation of water through the hollow supporting structure from one end to the other,

a series of separate rolling elements in contacting relation confined in a single line for movement along the track in the direction in which the objects to be heated are moved, the peripheries of the rolling elements in the track projecting above the track for supporting the objects to be heated at spaced intervals,

a return guide for receiving the rolling elements at one end of the track and returning them to the other, said guide being of tubular construction extending lengthwise through the hollow supporting structure with terminals that pass through the hollow supporting structure and join the ends of the track, the track and return guide forming a continuous elongated loop so that the separate rolling elements impart motion to one another and the rolling elements are cooled in their return movement through the guide,

the rolling of the elements in the tracks shifting their points of contact with the objects.

7. The furnace defined in claim 6 wherein the separate rolling elements are balls and the track is curved in transverse section to receive and confine the balls, said return guide being a tubing of an internal diameter through which the balls may freely move, but which retains the balls therein in a single line.

References Cited UNITED STATES PATENTS 718,760 1/1903 Hibbard 2636 2,744,758 5/1956 Stokvis et a1 193-35 X 2,928,666 3/1960 Distler 263-6 JOHN J. CAMBY, Acting Primary Examiner. 

1. A CONVEYOR FOR USE IN A FURNACE FOR HEATING SLABS AND THE LIKE COMPRISING: A HOLLOW ELONGATED SUPPORTING MEMBER, MEANS FOR CIRCULATING A COOLING MEDIUM THROUGH THE HOLLOW SUPPORTING MEMBER, A GROOVED TRACK CARRIED ON THE HOLLOW SUPPORTING MEMBER, A CURVED TUBULAR GUIDE AT EACH END OF THE TRACK EXTENDING INTO THE INTERIOR OF THE HOLLOW SUPPORTING MEMBER AND A TUBULAR GUIDE INSIDE THE HOLLOW SUPPORTING MEMBER EXTENDING LENGTHWISE OF THE SUPPORTING MEMBER AND CONNECTING THE INNER ENDS OF THE CURVED TUBULAR GUIDES TO FORM WITH THE TRACK A CONTINUOUS ELONGATED LOOP AROUND WHICH ROLLING ELEMENTS MAY TRAVEL, AND A CONTINUOUS PROGRESSION OF SEPARATE ROLLING ELEMENTS IN ABUTTING CONTACT MOVABLE AROUND SAID ELONGATED LOOP WITH THEIR PERIPHERIES OF THOSE ELEMENTS WHICH ARE IN THE TRACK PROJECTING ABOVE THE TRACK SO THAT THE WORK PIECES MAY BE SUPPORTED THEREON. 